Simpson Adhesive Retaining Cap for 1/2 in. Anchors and 9/16 in. Hole Diameter is a plastic anchoring accessory from Simpson engineered to make overhead, upwardly inclined, and horizontal adhesive anchor installations more reliable and precise. By sealing the mouth of the drilled hole, this retaining cap prevents anchoring adhesive from running out during rod or rebar dowel insertion, while simultaneously centering the anchor for accurate placement - making it an essential component wherever consistent embedment depth and rod alignment are critical.

Key Features

• Slit-style cap opening allows the insert to pass through while containing the adhesive in the hole - the anchor rod or rebar dowel seats cleanly without disturbing the adhesive seal, so you get a full, uninterrupted bond every time.
• Centers the threaded rod or rebar dowel during insertion into the drilled hole - eliminates off-axis placement and ensures the anchor is positioned correctly before the adhesive sets, reducing costly rework.
• Designed for overhead, upwardly inclined, and horizontal orientations as well as deep embedments - a single accessory covers the full range of challenging installation angles where adhesive retention is most critical.
• Works with any Simpson anchoring adhesive - no need to match the cap to a specific adhesive product, giving installers flexibility across different jobsite requirements.
• Compatible with the Simpson Piston Plug Delivery System - integrates directly into an existing dispensing workflow, keeping the installation process efficient and consistent.

Why This Product

• Solves the core problem of overhead and inclined adhesive installations - gravity works against you when injecting adhesive into upward-facing holes, and this cap keeps the adhesive inside the hole where it belongs until the anchor is set and the bond fully cures.
• Built-in rod centering removes a manual alignment step - rather than estimating rod position by eye, the cap physically centers the anchor during insertion, which is especially valuable in applications where precise anchor placement is required.
• Broad orientation compatibility means one product handles multiple scenarios - whether the application involves overhead concrete anchoring, inclined structural connections, or horizontal embedments, this cap performs across all three without substitution.
• Made in the United States and backed by the Simpson brand - engineered as a purpose-built accessory within the Simpson anchoring system, this cap is designed to work seamlessly with the same adhesives and delivery tools already trusted on the jobsite.

Specifications

• Brand: Simpson Strong-Tie
• Model: ARC50A
• Material: Plastic
• Bolt/Rod Diameter: 1/2 in.
• Hole Diameter: 9/16 in.
• Drill Bit Diameter: 9/16 in.
• Packaging: Packs of 25 and Cartons of 200
• Country of Origin: United States

Approved Applications

• Overhead adhesive anchor installations where adhesive retention is required
• Upwardly inclined anchor installations
• Horizontal adhesive anchor installations
• Deep embedment applications requiring precise rod or rebar dowel centering
• Use in conjunction with the Simpson Strong-Tie Piston Plug Delivery System

Frequently Asked Questions

How does the adhesive retaining cap prevent adhesive from running out of the hole?

The cap is placed at the mouth of the drilled hole and features a slit that allows the threaded rod or rebar dowel to pass through while creating a seal that contains the anchoring adhesive inside the hole during installation. This is especially important in overhead and upwardly inclined orientations where gravity would otherwise cause the adhesive to run out before it cures.

Can this retaining cap support the weight of the anchor during the adhesive cure time?

No. Simpson Strong-Tie adhesive retaining caps are not designed to support the weight of the anchor. For overhead installations, it is advisable to provide an adequate means of anchor support during cure time to ensure a proper and safe installation.

Is this cap compatible with all Simpson Strong-Tie anchoring adhesives?

Yes. The ARC50A retaining cap works with any Simpson Strong-Tie anchoring adhesive, and it may also be used in conjunction with the Simpson Strong-Tie Piston Plug Delivery System for added installation convenience.

What anchor and hole sizes is the ARC50A compatible with?

The ARC50A is designed for use with a 1/2 in. anchor (threaded rod or rebar dowel) installed into a 9/16 in. diameter hole drilled with a 9/16 in. drill bit. The cap centers the rod within the hole to ensure precise anchor placement during installation.

Note: Adhesive retaining caps are not designed to support the weight of the anchor in overhead installations. It is advisable to provide an adequate means of anchor support during cure time when performing overhead anchor installations.